Shonky CCTV power supply teardown
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- เผยแพร่เมื่อ 21 ก.พ. 2024
- This is a generic imported CCTV power supply bought from eBay. There are a few issues with it, mainly the quality of manufacture, electrical isolation and wire colour choices.
The large holes to allow a wide tolerance of the mounting pillars may shunt the positive rail to ground if too far off centre. If that happened and a circuit had the negative referenced to ground elsewhere it could result in quite a high current flow without any inline protection. Some insulating washers on the case mountings would avoid that.
The poor electrical clearance was completely avoidable. The Chinese manufacturers don't seem to be too fussed about separation between high and low voltage. Swapping the live and neutral would reduce that hazard, but that's a bodge fix.
The spare PTCs were puzzling until I saw how splayed the legs of the PCB mounted ones were. These components cycle thermally in use, so that may result in stress on the lead connections.
The switchmode power supply is a joy of complexity, with its low voltage controller chip controlling circuitry that has strong self-oscillating ballast type vibes. It almost looks like the unit starts self-oscillating to power the output and control circuitry, and then gets its feedback transformer magnetically shunted or controlled by the low voltage side.
I'd like to see a schematic for this unit. Reverse engineering it would be made tricky by the two custom wound multi-winding transformers.
It's an interesting unit, but not one I'd trust for a safety critical application.
Incidentally, the first cable I tested it with turned out to have a three pin plug and socket, but just two core flex connecting them. It was supplied with a studio light from eBay.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- www.bigclive.com/coffee.htm
This also keeps the channel independent of TH-cam's algorithm quirks, allowing it to be a bit more dangerous and naughty.
#ElectronicsCreators - วิทยาศาสตร์และเทคโนโลยี
You always know it was made with love and care if there are big splotches of solder over the circuit board.
They're 'love splotches'... Oh dear lord.
this is a very classic design, and closely follows the old "AT" and "ATX" power supply layout. the capacitor in series with the transformer stops flux-walking, which can eventually saturate the transformer core and cause your transistors to turn into grenades. it is wild that a little film capacitor is passing the entire current of the supply. the way it starts up is also pretty cool as you discovered; the two transistors form a push pull oscillator using the pulse transformer to get the power supply started, then the TL494 (guessing that chip is closely related) will drive the transformer and overpower the oscillation and then it will operate as a push-pull driver like you'd expect. It is a forward converter, which is better for the output capacitors vs. a flyback converter, so it can get away with much smaller and less capacitance even though it's rated for 10A output.
Indeed: the TL494 and the KA7500 are functionally identical.
11:47 "If you set it to 120V and you put it across 240 it'll go bang." Back in the 1990s I had a tower computer with a heavy sliding switch on the power supply to select 120V or 240V. I wanted to find out what it felt like to change the selection from 240V to 120V, so I pushed it across, forgetting to unplug it from the mains first.
Yes, it went bang.
i know that
Back in the Early 2000 i was the IT Guy in School.
So i Fixed PC's Build backup Systems.
Tested Computers.
Sometimes i forgot to lock my Door when i took a whiz.
So i had other atendees go into my room and Switch power supplys from 220 to 120 to prank me.
Usally i checked the one time i didnt it was a Big bang and then and the Power went out on the entire Floor level.
That was a Big talk with managment.
After That i Locked my Room Always when i took a Break or a Whiz, and double checked always so it never happend again.
I worked in a 240 V country with a bunch of North Americans. A mix of 110 and 220 V equipment.
I discovered that Compaq power supplies were not standard after I blew one up with the wrong voltage.
I am jealous. Mine just made a burning smell and took Motherboard of mine old 486 with it. Nothing cool to watch.
ah yes the magic switch. i too thought i wonder what happens if i set it to 120 (im in a 240 region). i thought hey - would it run half as fast? maybe i could get a quieter computer. i mean, i kinda did.
@@pepe6666 Quieter eventually. After the bang.
15:54 Channeling the Lock Picking Lawyer. He'd be proud, Big Clive!
Was waiting for the dumdums with LPL comments.
He even did it twice, to make sure it wasn't a fluke.
Well I use screwdriver to open these locks.
@@foogod4237
Was about to comment that XD
So what's next. Clive opening locks with his spudger and LPL cracking safes with a super capacitor.
Not even sure why you would bother picking the lock when you can just unplug it on the top 😂😂
Probably because the purpose of the lock is to keep unaware people from touching partially exposed high voltage connections.
@@RK-kn1ud Just like the purpose of most locks is to keep honest people honest. I don't know what the legal position is, but my view is that if you've picked a lock to gain access to some electrical equipment then whatever happens to you after that is entirely your own fault.
@@RK-kn1ud 230 V is low voltage.
@@mernokallat645 230v may not be considered high-voltage by the industry, but its high enough to maim or kill someone that doesn't know what they're doing. To the average Joe, USB is "low voltage" and wall AC is "high voltage."
Depends how the box is installed, could be installed into a frame where the plug is inaccessible, however like most "security devices" they only slow down the intrusion and cause more damage and expense to repair or replace.
Clive branches out to compete with Lock Picking Lawyer! lol
Only there is no suspicion that Clive is faking it.
We all know what Lpl would do and approx how quickly.
And Clive can actually say "This is a Fluke"
@@LeifNelandDk but he did try it again to prove it was not a fluke! 😁
@@magma2050Notice he capitalized the F?
He was referring to the _Fluke_ brand of measurement meters 😉
Thumbnail definitely got me... "Wait, that can't be real??" 😂
Of course if such a thing were real, Clive would be the one to find it and share it with us all.
Excellent box on the thumbnail!
Must make a screendump and save the pic!
thumbnail*
But yes. I did a double take, then I concluded that it had to be fake. Wasn't entirely certain though. One heck of an attention grabber! 😂
@@herrpezLoL it matches the title description which is perfect and funny 🤣
@@herrpez Yeah, I've been drinking 10,5% beer all afternoon. It's really a miracle I can use my computer at all.
I think in some countries they call it "malt liquor".😝
Of course it's fake! Clive does that all the time.
Awww, I wanted that to be real.
The box caption channels my inner and not very repressed Butthead. 😂
The power supply with the self oscillating through the driver transformer and TL494/KA7500 control IC is the same like PC AT power supplies and also the first ATX power supplies were back in the 90's before PFC became a requirement. The TL494 only comutates the transistors, the drive power still mainly comes through the feedback winding. It's a cool circuit, I converted some of those to drive and dim Flourescent tubes back in the day.
That right there is a cheap and crappy wafer lock. Looking at the bitting, it's a common one used in cheap cabinets and some roof racks for cars-if you'd given it a saucy look it would have opened for you. A zip tie could open it.
Otherwise, it's an interesting little case/PSU combo. Those 240/120 switches were fantastic to watch the result of when some kid had flicked them on the back of their computer's PSU. I had one actually shoot a jet of flame out when powered (deathbeam cap rupture and ignition).
It would be interesting to hear an electrical engineer & security/hacking type individual explain how these type of consumer devices can be designed in a way that increases or decreases the ability of outside actors to influence/control them…
I mean realistically the point of that lock is really just to make sure that nobody accidentally opens it. If you pick the lock with a piece of grass from the lawn, well you still picked the lock so it's not the owner's fault if you get hurt. But yeah the better option is to protect access to the location the unit is in anyways, since a nice thwack with a hatchet will do the job without even bothering with the lock.
It's always nice when your new purchase comes with spare parts. It is also a HUGE WARNING SIGN!
"I'll do it again, to prove to myself that it wasn't a fluke"
*an amecal
Standard self oscillating power supply with secondary side regulation. Circuit is exactly like the cheap PC power supply using a 3524 regulator, of which there are hundreds of designs available online with operation. On power on the primary side starts to oscillate, from a small diac in the circuit, like in a CFL lamp, and then this provides a bootstrap power to the controller, which then drives the small transformer with current pulses that force it to switch at a much higher frequency, so the diac circuit is not going to fire again to start the oscillation, and the power supply will regulate using the pulse width and dead time of the drive pulses. Starts off with a low frequency, and you will find the unit will stay in this mode if you apply power with a shorted output, it ticking along at a few hundred hertz attempting to bring up the secondary rails to a high enough voltage so the controller comes out of undervoltage lock out.
First time I read about this kind of powersupply was years ago in the homo ludens website publishing a diy version (13.8v 40a) and it's quite clever. It eliminated the optocoupler and the control circuitry is isolated from mains so it's relatively safe to test and easier to implement both voltage and current regulation.
As a hobbiest electronics hacker, I wish I understood more about SMPS. It would definitely help if I knew anything at all about magnetics. :-\
it;s not though, it's not self osillating , it doesn't have a diac, it has a ka7500 aka tl494
This is not really a self-oscillating power supply. Whilst it starts by a kick from the primary it is ultimately driven by the KA7500 PWM controller chip below which drives the bases of the transistors via a gate drive transformer (the smaller yellow transformer). There is no diac in the circuit, like in a CFL lamp, but such a part is not needed for rudimentary operation. Usually these supplies start by a small current flowing into the base of one transistor from a high value resistor, which pulls enough current through the transformer to kick the PWM controller to life. The feedback/supply winding is consequentially a bit oversized so as to power the controller with a smaller kick than a conventional bootstrap circuit.
I think the PTC devices were an upgrade to the product, given the lead spacing and board silkscreen as a clue. I bet they initially provided spare fuses (which is sensible), but continued the practice with PTC's, not knowing any better.
Exactly. Another indication is that they are named "the insurance tube" on the label, which might be an odd description of a glass fuse.
Function of Protect
The "CAUTION!" sticker had it right I guess? Live being green makes sense -- the vast majority of living biomass is green (algae and plants); with the same logic I use brown for earth. Not always, of course, you gotta keep some surprises in your routine.
And blue is the ocean that swallows everything without change?
At least that's what people long believed, until trash banks started to form XD
Thanks Clive. Looks like a sort of hashed together product done by someone who didn't really know what they were trying to make but very interesting nonetheless. Liking the nod to Lock Picking Lawyer too 😀👍🏼
LPL great channel, the lock is pants however in UK Law having a keyed lock or mechanism that involves a tool to gain entry would enable a more successful prosecution of mischievous individuals.
...just to see if it was not a Fluke! Faster than LPL.
With the mains tracks so close to the secondary side, it's not just crappy - it's criminally shitty.
"You are using a cheap Chinese power supply lock which can be opened using a cheap Chinese power supply lock." _smashes box open with another power supply box_
I usually go with Long Dong Kok Shenzhen PSUs LOL
I've never encountered the Bang Dong... label until today.
Thanks for the interesting content. Keep up the great work.
I love the Chinglish information on the inside of the "Front Door". Also those wafer locks are so easy to defeat, it is certainly there for "visual effect" rather than functional security. As for the line and neutral situation, you could safely reverse the incoming connections, so having the neutral adjacent to the distribution side (although that means your PSU is switched on the neutral return). It would be far safer to strip off all the copper on that bit of the PCB and substitute a DPST switch in its place,(and use flying leads as appropriate). There's also enough space to Dremel an isolation slot beside the power terminal if needed - wouldn't be a bad idea at all!
Somewhat scarily, this looks VERY like the camera PSU they have in The Wife's Pharmacy - even down to the lettering beside the "DC12V" LED, although hers is green. Same number of distribution ports too. I will have to have a look inside this evening when she closes up!
I’ve been using this exact power supply everyday since 2020 it’s been working absolutely great I had no issues with it at all
Looking at this it seems you've been very lucky 😂
@@skylined5534 why is he lucky? the main psu is a solid design
@@lezbriddon Because when the manufacturing quality is what it is.. you may or may not get a decent one. Or you may get something with a bunch of loose metal parts going around exploding.
@@skylined5534 The 12V PSU that came with my Anet A8 printer kit looked exactly like it. I think it ran fine for about 4-5 years before crapping out.
@@benbaselet2026 there's no loose bits in that PSU, there's loose bits in the case that's holding the PSU..... While it could lead to the same outcome from shoddy workmanship the people doing that no doubt just bought in that PSU and have never been inside it. I'll stand on the PSU being very reliable in itself.
The box thumb nail was perfect, if was real I wouldn’t of been surprised it was that good thanks Clive 😊
The first thing that caught my eye was the switching power supply, full of ventilation holes, locked inside a closed metal box...
The second thing was the key, "securely" locking the box, while you can easily unplug the power cable and disable all ten cameras at once...
Man, that was timely for me. I just ordered a 24 volt version of that same-ish power supply. Thanks for teaching me how to make sure this s**t doesn't kill me. I'm about to plug it in and see what's up.
Like the voltage doubler for the 110V people. That’s quite a clever way of achieving it.
I saw it for the first time on a job interview test. Had to work it out analytically to figure out what it was doing, and my mind was blown.
Such a simple way to do the selector, yet I had never given it much thought.
I think most PC power supplies from the 90s to naughties used that same system, before PFC was a thing. Definitely important, though... I bought my identical supply in the USA and it came shipped in the 240v position. I guess they're all shipped that way, since if someone plugs it in without checking, it's a lot less dangerous than the other way around. (I mean, the inductor caught fire a few months later, so even set up right these SMPSs are still dangerous.)
Bang Dong Kok? Sounds like Bang Ding Ow from that Asian flight that had Sum Ting Wong and We Tu Low as the pilots.
Enough about that! Where your wheelie bin?!
@@skylined5534 Outback wif da fellas.
Ho Lee Fuk!
Great video as always. The Lock Picking Lawyer would be proud of your skills!
I like how secure the power feed is with a normal C13 plug. So if you want to shut down the cameras, you only need to unplug it. 😂😂
Well, realistically, there's all kinds of ways you can do that anyway (e.g. cut the wires going to the cameras, etc). If this is for something like security cameras, the power supply box (and all the related cabling) should be located in a properly secured location anyway. I'm pretty sure the lock on the case is mainly just to stop some random person who doesn't know what they're doing opening it up, sticking their fingers in there and shocking themselves or damaging something...
Which is also why it doesn't really matter that much that it's a crappy lock, too, because it's mostly just a reminder of "if you weren't given the key, you shouldn't be opening this", not something intended to try to keep someone out if they're really determined.
(It may also be partly to comply with various regulations that say that anything that has exposed mains wiring inside must be able to be closed in a way that can't be easily opened by children, etc.)
Didnt even look at the title, just saw the box, thats enough for me
Glad to see you picked it twice to show it wasn't a fluke.
That lock picking reminded me of the old Keden padlocks, You could pick them with a piece of clock spring, when I worked for a hardware store and lock smiths for a few years in 1971 in Cambridge we got called out just about every day by someone who had lost the keys to their lock and a bit of spring was all we used on most bike locks. A good piece of rope and a dozen knots would have been more secure.
Cabinet locks I used to pick them with 2 paper clips, as after all you could be expected to use a paper clip to hold 2 bills together, and having 2 just meant you had a spare one.
One is binding, and it's open. Let's try again just to show you it was not a Fluke.
Is it a MasterLock, perhaps?
LockPickingClive 😂
Love your videos and what you do and how you engage pretty often with comments and your viewers
Thanks.
The wiring colors remind me of something I found in my dad's house wiring. Neutral was black, L1 was red, L2 was white. Electricity doesn't care what color the wire is as long as it goes to the right place. Same in refrigeration, we had guys that got complacent ALWAYS assuming R/W/Y/G/C/B/H/O colored wires were actually what they thought, rather than tracing the wire or doing any testing. They would've had a stroke trying to work on the old Lennox heat pumps that used yellow wire for EVERYTHING.
It can be confusing in the UK with Harmonised colours, I notice a Black cable going to Neutral Bus in a substation having an upgrade just when UK Harmonised to EU colour. Before N was Black the Red Yellow Blue for Phases. Black was now a Phase conductor along with Grey and Brown, Blue then became Neutral. I called the engineer who was installing the new cables which had yet to have final test. The line when't quiet before many fruity expletives. Apropos your post, I thought Black to be hot and White Neutral as in the US.
Wiring is actually conforming to Chinese wiring practice. Those 3 colours are used there for this, which makes it rather confusing to people outside, who get those 3 odd colours. I found it best to replace the cable anyway, simply because the thin cheap cable used would invariably fail with minimal use.
The guy who installed the HVAC in my house consistently used the orange wire for the W terminal, because he thought he was wiring it for a heat pump but it ended up being conventional. And, of course, many thermostats mark that terminal as "W/O" and change its function depending on their settings. The zone controller can also handle either type of control, but it has separate W and O terminals. On the zone controller end, all of the orange wires went into the W terminals.
If the guy had remembered to set the zone controller and the thermostats to conventional control, it would have worked. Sadly, that was just the first and simplest of a lot of different mistakes that guy made.
@@Woffy. We had a lot of new equipment damaged during the transition when black and blue were swapped and contractors connected the old colour code to the new one. It was one of the most idiotic colour code changes imaginable.
@@bigclivedotcom So the rest of the EU should have changed instead?
It looks like the things we had to do create in the very early days of LED reef aquarium lighting when nothing was readily available. 😅
That power supply looks exactly like the one I was using to drive some LEDs until I came home and smelled fire and discovered the output inductor had caught fire. I pulled it, rewound a new coil, replaced the burnt caps, cut a hole in the case, installed a PC fan directly over the inductor, and put it back to work. Still have the black scorch marks on the wall where it was mounted.
Hey that's my favourite pick too 😂 those locks are extremely easy to open normally. Just a deterant. Great video as always. 👍👍
Lock for security but you can just yank the power cord?
Some of my workplaces have 'security' installations run with metal conduit having tamperproof Torx screws on the conduit box covers, but the circuits are fed from 'normal' MCBs in an unlocked panel!!
@@stepheneyles2198 "tamper proof torx screws" that anybody can unscrew with a 5$ hex bit kit? The whole "tamper proof screw" is a meme. A real "tamper proof screw" has the head's "screwdriver holes" drilled off so you can't unscrew them, period
i think that lock is more a stray finger deterrent than an actual anti break in measure, an open door is inviting to fools, while even simply having it closed can prevent alot of trouble
I have used one of these supplying power to 6 external hard disk drives of various types and capacities as my TV and film collection grew with no problem previously. I did do a full check inside before using it. It's quite a nice compact supply for this and I had no problems.
The box looks quite similar to the power supply of the alarm installation we had from the 1990's to the 2000's in the family company.
At work they were ordering units identical to these, and the larger model with twice the outputs, when I needed a new P/S for a CCTV service call. Not having fuses was a plus, but the power supply it self would fail at times. Certainly not built near as well as the old style with a standard transformer rather than a switching power supply. Thanks for highlighting this product Clive.
supply has its roots in early at/atx supplies and are often tl494/598 based, very reliable.
Very reiiable until the electrolytics for biasing the primary side switch mode transistors fail. I recently had one of those AT supplies go bang on me. The 1µF/50V cap on one of the transistors showed as 950nF (not too shabby) and 0.14kOhm ESR (ouch!) on a TC-1. While I won't assume any kind of precision on this cheap tester, seing the ESR displayed in Kilo-Ohms was a surprising experience.
Actually, I missed the broken capacitor on the first repair attempt, but noticed a "smell like burned dust on a CRT" after swapping the usual components that blow on a primary side short. I already noticed that one of the transistors obviously got excessively hot, becaus its plastic insulating bushing was molten to the transistor. Because the bushing was molten, the screw was no longer pushing the transistor to the Sil-Pad. I first imagined the failure sequence to be a dodgy transistor getting to hot, and in consequence losing contact to the heat sink due to the failed bushing and getting even hotter until it broke down.
As the "smell of really hot electronics" did not go away on a couple of minute-long test runs after working on that supply, I found out that the primary transistor heatsink was extremely hot, and especially that the transistors were not equally hot, pointing to some failure in the transistor driving circuit (which was correct: the electrolytic mentioned in the first sentence). You can easily diagnose problems in the base drive circuit by just powering the TL494/KA7500 from any standard 12V power supply. Even without dangerous live primary voltage applied, the base waveforms are viewable on a scope (and already the different average DC base voltage clearly indicated a failure in one of the transistor drive circuits.
@@tw11tube didnt know the 12v supply trick thanks for mentioning that
I have never seen a more trollish box in my life!
"BANG DONG KOK SHENZHEN KRAP-U-LUV"
Now that's my kind of humor.
A real blast from the past - these were fairly common 10-15 years ago. These days we use poe or an injector if its a remote / lone cam. So much easier now
15:15 I love that "erm" like you did more than open the cover lol
You had me going with that thumbnail, Clive. Well played, Sir.
Great stuff. Amazing to see the complexity of those generic smps units. You got a click out of every pin from what I saw :D.
It's not a fluke. Clive is the Lock Picking Electrician.
We use a voltage doubling power supply to get 600V dc of a 240V mains supply.
That we feed into a vsd and can run 400V 3 phase motors off 240V single phase.
A resistor with bypass contactor is used to charge the caps on power up.
Also we do add extra caps to reduce the dc ripple to the same level that one would have had off a 3 phase supply.
This was a good video, thanks for sharing.
Loved the thumbnail, I'm surprised TH-cam allowed you to use it. That said the TH-camr Diode Gone Wild has torn down a series of Chinese powersupplies and at least one of those turned out to be based on an AT computer power supply, it even had a fan header, not that the power supply itself had a cooling fan fitted.
Thanks Clive love the box. Looks like one of those low security key safes , might just be one of them repourpoused
Everybody talking about the booms from the 240-120v switch, in NA when we flick the switch nothing happens
Krap-U-Luv !! LMAO. I fell for it. Given that the briefest of searches for any electronic device these days yields many "brand names" that are so improbable. I get a kick out of them.
There's something about these imports and not following standard wire color standards. My brother's laser engraver died due to failed laser power module. He got in an upgrade for it and we set about putting the new one in with a wire diagram and schematics in hand. When we opened the lid, we were in shock to find the manufacturer used yellow wire for every connection except for earth ground where they used a green and yellow striped wire!
Using the colored wire diagram, we used same gauged wire and matched the colors shown on the diagram. Power on the digital side was in red, ground in black, and other signals in green, yellow, and blue. The process took us a few hours and after checking our connections multiple times we powered the unit up and it worked with one small hitch. We neglected to ground the water-float sensor on the power module. Some lasers use an automatic shut-off for the water cooling system should the water drop too low below the gas tube. Since we don't have that on this unit, the signal had to be grounded out.
You got me there with the thumbnail. I actually hoped they're so self-(un)aware to actually print that 🙈
This is something I am still looking for. In UK it seems like a choice between Elmdene. Unfortunately being the only reasonable one they charge premium and their supplies are mediocre or budget grade at best. I would love to find one of these boxes with PTC fuses even if in plastic which would take a good quality supply like Stantronic (RS pro) or Meanwell, but for years with no luck. The lock is not there for security, but more as an access control, to stop onside technician/decorator from taking supply of one camera non-working and connecting to another circuit shared with another camera taking more of them off. But I know you have wanted to showoff your picking (raking) skills.
I consider something of this size overkill for LEDs as they would run happily from any cheap inline supply.
That power supply looks like one of those run of the mill MeanWell power supplies that is littered all over ebay and amazon. They're really popular with the Commodore 64 crowd for rebuilding the shoddy power supplies that came with those computers. Naturally they use the 5 volt version.
Or one of a million Mean Well look alikes.
Did they use a hammer and a punch to create the hole for the red LED? Nice! 🔨
The isolation issues on the PCB can be obviously made irrelevant by simply connecting the incoming AC flex from the IEC socket directly to the power supply terminals. The silly switch on the board is completely unnecessary given the fact that you can just unplug the input power at the IEC connector to turn off the power.
Thanks for uploading clive! That power supply is of quite an old-fashioned style. Btw, the 7500 chip is very similar to the TL494, if not the same.
Wow Clive, just, wow.
Loved the LockPickingClive crossover!
An engineer I know ordered a STATCOM from China for a solar farm grid connection. When it turned up they discovered every single control wire was done with green coloured cable
Oh I thought this was one of those control boards for a CRT TV. Adrians digital basement got one and swapped it and surprisingly it worked pretty well.
I'm "shocked" that Clive didn't say anything about the mounting instructions mentioning the "Buttom" 😂😂🤣🤣
That chip 7500BD was used a lot in 1990-2000's era PC power supplies._
oh nice, this looks like the kind we had at the factory
The power supply circuit is probably quite similar to an old PC (AT style) supply, which did not use additional standby converter but its startup relied on the power stage self-oscillating. Then typically a pair of NPN transistors (C945) controlled by the IC take over driving of the feedback/driver transformer. 7500 IC is largely compatible with the well known TL494.
I absolutely adore polyfuses. Clive hasn't been half enthusiastic enough about them. They are available in just about any current rating from a few milliamps to several amps - and I use them on lots of my 12v stuff. Just don't put them touching any low melting point plastic :)
"How long will it take me to get into it's open."
Lmao.
I have a 5V power supply that looks almost *identical* to that one inside. I didn't look at component values or even the back of board but at a glance I only noticed a few very marginal differences: the bridge rectifier is a single component, a single higher watt resister near the large electrolytic caps instead of 2, 3 jumper wires in the middle instead of 1, and the 3 blue caps near the input/output connectors are on a diagonal.
Inductors was one thing I never became familiar with. I am fascinated by them. I didn't know about how useful they are. I understand a lot of components, but inductors and special diodes, transistors, and resistors, I also am not familiar with how they work. But I am trying to learn.
And learn how all the components work together.
Everyone saying the lock is for security and makes no sense when you can just unplug it. It's probably more about protecting random access to the mains voltage from the uneducated. But marketing may try to sell it as a security lock, which is a nice generic term, let the customer interpret what is actually being secured.
7500 is a clone of TL494. The whole power supply is just like an AT computer power supply, except with only the 12V output. Quite old school.
Clive. When you said Euro Plug I thought there's a quicker way to turn off the cameras (if I were breaking in somewhere). Pull the plug.
Security? Comical! 😆👍
I used to see these all the time in Canada for CCTV systems. The thermistor issue makes sense to me. The only times I'd see these somewhat fail was when one of the channels would just stop working and not reset. Usually there were spare channels so a pretty easy fix. I never saw one fail completely, as usually the cameras would age out before the power supply.
That pcb is clearly not a mass production and the whole thing seams hand made to the exception of the psu.
Thanks for the lock picking entertainment and it was also very informative. The next time I'm at work having to deal with opening a box I'll give the pick a try before looking for the keys only to find out no one knows where it is and safe my drill bits ant time replace the lock 😅
LPLxBigClive collab! 30 seconds for LPL to open an electronic lock because of how bad it is, and the other 39 1/2 minutes of Big Clive explaining how bad it is!
I’m now wondering how similar the board’s schematic will be to the generic schematic on the chip’s datasheet.
Many years ago I was tasked with designing a supply and selector box to take inputs from a dozen cameras and feed them to four monitors on command. All in one box, much simpler supply because the cameras were 120V and much more robust than today’s typical 12V units (and had to be independently powered from the rest of the plant grid for security if the power went down via a beefy UPS), and the cameras had to be switched by computer control. It was a complete hairball but it worked and in three years we had no failures. Honestly I did what I described above- figured out what chips I wanted to switch the video feeds through and cribbed straight from the datasheet.
Some things never change.
that PSU setup is oddly reminiscent of old Baby-AT and XT computer power supplies from way back in the day before 5V-Standby was a thing. I haven't seen an HV-transistor driver transformer in a PSU in a very long time.
Top quality hardware there, locked to stop people switching it off, but with a nice easy to disconnect C13 cable on the outside, top security there... :P
Kept thinking you were saying soda, instead solder... I was like damn the builders were messy
I've raked open multiple locks like that with a bent paperclip and a screwdriver for tensioning, they're really cheap and nasty.
You can usually do it with just the paperclip if you bend the wire into a tight U shape and put a little torque on it.
When you said you would draw a doodle, you had us worried for a sec...
Thanks Clive. Nice find. Pity about the faux security.
For the RF folk. This particular SMPS (model number @ 0:05 )
Is radio-quiet. No RFI, QRM, etc. Mod's easily to 250w 14v 90+%.
I'm surprised it's low noise.
The Common Mode Choke and Caps work really well in this confg'.
The low quality output Caps actually work in favor of filtering because of their wide differences. I bought one to test 5~6yrs ago, and was pleasantly surprised.
Adding a 50,000uf 35v Cap to the output makes a perfect Radio psu.
Those PTC seem to have a finite amount of trips they can perform till their own inner resistance starts to gradually creep up and then eventually they may trip for no reason...
We stopped using that type of power supply and went to weidmullers or Schneider .We made our own distribution blocks with din rail and terminal blocks .
More than 30 years ago, when computer power switches switched the incoming mains directly, one of my coworkers turned on a PC with its power supply switched to 110V. It was like two camera flashes going off simultaneously - one inside the power supply, the other inside the power switch itself. The bang made everyone in the shop turn and look. I still remember how fast he jumped back and held his hands up as if being threatened with a gun. The boss made us check every PSU from then on even though it was the only one to ever be set incorrectly.
I once did that to a brand new and expensive disco light. It took out every single stepper motor chip.
16:11 - He done it again to make sure it was not a fluke 😀
Looks a lot like the circuit beakers in that "lethal company" game 😀
Old fashion wiper blades have metal pieces that look like lock pick tools.
Street sweeping machine brush bristles are good too.
Best thumbnails on TH-cam. 😂
The main issue I have with this style of power supply - at least the 5v dc model I have. I get a 3v reference to the AC side. The explanation of the 120/240 switch explains why.
Oh yes that power supply looks like a fairly standard unit. I picked up one a few years ago with the intention of putting all my networking gear that was 12 V on a centralized power supply and well I'm only just getting there now. I have essentially turned it into a central battery with it feeding some radios and socket for plugging things in and Anderson cables to three Anderson breakout panels. I have it set up to charging some 12v5A SLA batteries like nine of them in parallel ( I had a large UPS that I replace the batteries in all at once as one of them exploded. but all of the other 9 were still good. Unfortunately not long after the entire UPS died catastrophically with that transistors which I tried to replace buying new components off Amazon that ended up being used, but still not sure that's the only issue with the board gave up and bought another unit ). I wired it up through some diode's and that splits two ways to a board that shuts off the batteries when the voltage drops and then that goes into a Buck boost regulator to put out stable consistent 12v until the battery protection module shuts off. It's been sitting there on ( like a Frankenstein project with life support cables ) for at least 3 or 3 years now with the occasional power outage. I think I went with the 35A module?
There are versions with standard fuses instead of PTC's. The green output LEDs just indicate the status of thoses fuses, 1,5A AFAIR.
If you have one of those nail clippers with the little nail file on the back, the nail file works well to pick those cheap water locks.
One major problem I see is that its got an external IEC power plug which completly underminst the "Security" aspect of having a locked box...
That bit with the voltage selector switch reminds me of what I've seen in a LOT of computer power suppliies. Is that AC inlet that you referred to as a Euro standard what I'd call an IEC socket? I have a couple of similar power supplies, one rated at 10A and one at 25A or 30A, to run my ham radio station. I built my own DC distribution box to handle the output of that stuff. The lighter one I use as a bench supply for stuff that wants 12V. I've never opened them up at all, nor investigated the circuitry. That particular form factor seems to be available with a number of different voltages, probably 5V and up to I think 48V or perhaps even higher, something I'd considered if I ever get my CNC project off the ground...
good job on the Thumbnail photo :)
The 230 V-connector on top shows that they do not think too much about their design. Wall mounted devices should have outlets preferrably on the bottom side in case water is pouring down.